Rhenium-free single crystal superalloy for turbine blades and vane applications

ABSTRACT

A rhenium-free nickel-base superalloy for single crystal casting that exhibits excellent high temperature creep resistance, while also exhibiting other desirable properties for such alloys, comprises 5.60% to 5.85% aluminum, 9.4% to 9.9% cobalt, 5.0% to 6.0% chromium, 0.08% 0.35% hafnium, 0.50% to 0.70% molybdenum, 8.0% to 9.0% tantalum, 0.60% to 0.90% titanium, 8.5% to 9.8% tungsten, the balance comprising nickel and minor amounts of incidental elements.

FIELD

Disclosed are single crystal nickel-base superalloys exhibiting excellent high temperature creep resistance, while being substantially free of rhenium, without deleteriously affecting other relevant characteristics.

BACKGROUND

Because of a worldwide growing demand for products that have customarily required substantial quantities of relatively scarce metal elements, both the demand and prices of rare metal elements have sharply increased. As a result, manufacturers are searching for new technologies that will reduce or eliminate the need for these metal elements.

Rhenium is an example of a truly rare metal that is important to various industries. It is recovered in very small quantities as a by-product of copper-molybdenum and copper production. In addition to its high cost, use of rhenium presents a supply chain risk of both economic and strategic consequence.

Rhenium has been widely employed in the production of nickel-base superalloys used to cast single crystal gas turbine components for jet aircraft and power generation equipment. More specifically, rhenium is used as an alloying additive in advanced single crystal superalloys for turbine blades, vanes and seal segments, because of its potent effect at slowing diffusion and thus slowing creep deformation, particularly at high temperatures (e.g., in excess of 1,000 degrees C.) for sustained periods of time. High temperature creep resistance is directly related to the useful service life of gas turbine components and engine performance such as power output, fuel burn and carbon dioxide emissions.

Typical nickel-base superalloys used for single crystal castings contain from about 3% rhenium to about 7% rhenium by weight. Although rhenium has been used as only a relatively minor additive, it has been regarded as critical to single crystal nickel-base superalloys to inhibit diffusion and improve high temperature creep resistance, it adds considerable to the total cost of these alloys.

From the foregoing discussion, it is apparent that it would be extremely desirable to develop single crystal nickel-base superalloys that exhibit excellent high temperature creep resistance, while reducing or eliminating the need for rhenium additions, and while retaining other desirable properties such as good castability and phase stability.

SUMMARY

The rhenium-free single crystal nickel-base superalloys disclosed herein rely on, among other things, balancing the refractory metal elements (tantalum, tungsten and molybdenum) at a total amount of about 17% to 20% in order to achieve good creep-rupture mechanical properties along with acceptable alloy phase stability, in particular, ensuring freedom from excessive deleterious topological close-packed (TCP) phases that are rich in tungsten, molybdenum and chromium, while substantially eliminating rhenium from the alloy.

It has been discovered that a rhenium-free single crystal nickel-base superalloy exhibiting excellent high temperature creep resistance and other properties well suited for used in casting gas turbine components can be achieved in an alloy composition containing 5.60% to 5.85% aluminum by weight, 9.4% to 9.9% cobalt by weight; 5.0% to 6.0% chromium by weight, 0.08% to 0.35% hafnium by weight, 0.50% to 0.70% molybdenum by weight, 8.0% to 9.0% tantalum by weight, 0.60% to 0.90% titanium by weight, 8.5% to 9.8% tungsten by weight, and the balance comprising nickel and minor amounts of incidental elements, the total amount of incidental elements being substantially less than 1% by weight.

In accordance with certain embodiments, the incidental elements of the alloy is controlled to maximums of 100 ppm carbon, 0.04% silicon, 0.01% manganese, 3 ppm sulfur, 30 ppm phosphorous, 30 ppm boron, 0.1% niobium, 150 ppm zirconium, 0.15% rhenium, 0.01% copper, 0.15% iron, 0.1% vanadium, 0.1% ruthenium, 0.15% platinum, 0.15% palladium, 200 ppm magnesium, 5 ppm nitrogen, and 5 ppm oxygen, with each of any other incidental elements being present as a trace element as a maximum of about 25 ppm.

In accordance with certain embodiments, the trace elements in the incidental impurities of the disclosed nickel-base superalloys is controlled to maximums of 2 ppm silver, 0.2 ppm bismuth, 10 ppm gallium, 25 ppm calcium, 1 ppm lead, 0.5 ppm selenium, 0.2 ppm tellurium, 0.2 ppm thallium, 10 ppm tin, 2 ppm antimony, 2 ppm arsenic, 5 ppm zinc, 2 ppm mercury, 2 ppm cadmium, 2 ppm germanium, 2 ppm gold, 2 ppm indium, 20 ppm sodium, 10 ppm potassium, 10 ppm barium, 30 ppm phosphorous, 2 ppm uranium, and 2 ppm thorium.

In accordance with certain embodiments in which enhanced oxidation resistance and/or coating and thermal barrier coating (TBC) life are desired, sulfur is present at a maximum amount of 0.5 ppm, and lanthanum and yttrium are added to target an amount of total lanthanum and yttrium of from about 5 ppm to about 80 ppm in single crystal components cast from the alloy.

In accordance with certain embodiments used for large industrial gas turbine (IGT) single crystal component applications requiring low angle boundary (LAB) strengthening up to 12 degrees, carbon is added in an amount from about 0.02% to about 0.05% by weight and boron is added in an amount from about 40 ppm to about 100 ppm.

In addition to achieving excellent high temperature creep resistance in a substantially rhenium-free composition, certain embodiments of the disclosed single crystal nickel-base superalloys have a desirably not excessive density that is about 8.8 gms/cc or less, such as 8.79 gms/cc (kg/dm³).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are optical micrographs showing the fully heat treated microstructure of castings of a disclosed embodiment (LA-11753, CMSX-7, test bar #C912, fully heat treated, primary age 2050° F./4 hours).

FIGS. 2A, 2B and 2C are scanning electron micrographs of the microstructure of fully heat treated castings from embodiments disclosed herein (LA-11753, CMSX-7, test bar #C912, fully heat treated, primary age 2050° F./4 hours).

FIGS. 3, 4 and 5 are Larson-Miller stress-rupture graphs showing the surprisingly good creep strength and/or stress-rupture life properties of single crystal test bars and turbine blade castings made from the disclosed alloys.

FIGS. 6A, 6B and 6C are optical micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #D912, 2050° F./15 ksi/141.6 hours, gage area).

FIGS. 7A, 7B and 7C are scanning electron micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #D912, 2050° F./15 ksi/141.6 hours, gage area).

FIGS. 8A, 8B and 8C are optical micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11807, CMSX-7, mini-flat #53701Y-F, 2000° F./12 ksi/880.0 hours, gage area).

FIGS. 9A, 9B and 9C are scanning electron micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11807, CMSX-7, mini-flat #53701Y-F, 2000° F./12 ksi/880.0 hours, gage area).

FIGS. 10A, 10B and 10C are optical micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #B913, 1800° F./36 ksi/151.1 hours, gage area).

FIGS. 11A, 11B and 11C are scanning electron micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #B913, 1800° F./36 ksi/151.1 hours, gage area).

FIGS. 12A, 12B and 12C are optical micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #A912, 1562° F./94.4 ksi/100.9 hours, gage area).

FIGS. 13A, 13B and 13C are scanning electron micrographs showing the post-test phase stability of the disclosed alloys, which exhibit excellent phase stability and no TCP phases (LA-11772, CMSX-7, test bar #A912, 1562° F./94.4 ksi/100.9 hours, gage area).

FIGS. 14A, 14B and 14C are optical micrographs showing the fully heat treated microstructures of CMSX-7 MOD B single crystal test bars.

FIGS. 15A, 15B and 15C are scanning electron micrographs showing the fully heat treated microstructures of CMSX-7 MOD B single crystal test bars.

FIG. 16 is a drawing in cross section of a single crystal solid turbine blade cast from an alloy as disclosed herein which has the facility to machine both mini-bar and mini-flat specimens for machined-from-blade (MFB) stress-rupture testing.

FIGS. 17 and 18 show the tensile properties of the alloys versus test temperature.

FIGS. 19A, 19B and 19C are optical micrographs showing post test microstructures from a long term, high temperature stress-rupture test of an alloy as disclosed herein (LA-11891, CMSX-7 MOD. B, test bar #M923, 2000° F./12 ksi/1176.5 hours).

FIGS. 20A, 20B and 20C are scanning electron micrographs showing post test microstructures from a long term, high temperature stress-rupture test of an alloy as disclosed herein (LA-11891, CMSX-7 MOD. B, test bar #M923, 2000° F./12 ksi/1176.5 hours).

DETAILED DESCRIPTION

The alloys disclosed herein will be referred to as “CMSX®-7” alloys. This is the designation that will be used commercially, the expression “CMSX” being a registered trademark of the Cannon-Muskegon Corporation used in connection with the sale of a family or series of nickel-base single crystal (SX) superalloys.

The alloys disclosed herein are alternatively described as being rhenium-free, or substantially free of rhenium. As used herein, these terms means that the alloys do not contain any added rhenium and/or that the amount of rhenium present in the alloy is a maximum of 0.15% by weight.

Unless otherwise indicated, all percentages are by weight, and all amounts in parts per million (ppm) refer to parts per million by weight based on the total weight of the alloy composition.

Single crystal superalloys and castings have been developed to exhibit an array of outstanding properties including high temperature creep resistance, long fatigue life, oxidation and corrosion resistance, solid solution strengthening, with desired casting properties and low rejection rates, and phase stability, among others. While it is possible to optimize a single additive alloying elements for a particular property, the effects on other properties are often extremely unpredictable. Generally, the relationships among the various properties and various elemental components are extremely complex and unpredictable such that it is surprising when a substantial change can be made to the composition without deleteriously affecting at least certain essential properties.

With the embodiments disclosed herein, refractory metal elements (tantalum, tungsten and molybdenum) were maintained at a total amount of from about 17% to about 20% by weight, while balancing the amounts of the refractory elements to achieve good creep-rupture mechanical properties along with acceptable alloy phase stability (freedom from excessive deleterious topological close-packed (TCP) phase—normally tungsten, molybdenum and chromium rich in this type of alloy). Chromium and cobalt were also adjusted to ensure the required phase stability. The high amount of tantalum (approximately 8%) was selected to provide excellent single crystal castability, such as freedom from “freckling” defects. The amount of titanium (approximately 0.8%) and tantalum (approximately 0.8%) were adjusted to provide low negative γ/γ′ mismatch for high temperature creep strength and acceptable room temperature density (e.g., about 8.8 gms/cc, such as 8.79 gms/cc). Aluminum, titanium and tantalum were adjusted to attain a suitable γ′ volume fraction (Vf), while the combination of aluminum, molybdenum, tantalum and titanium were selected to provide good high temperature oxidation resistance properties. The amount of hafnium addition was selected for coating life attainment at high temperatures.

Typical chemistry for the alloys disclosed and claimed herein are listed in Table 1. However, there are certain minor variations. First, in order to achieve enhanced oxidation resistance and/or enhanced thermal barrier coating life, it is desirable to add lanthanum and/or yttrium in amounts such that the total of lanthanum and yttrium is targeted to provide from about 5 to 80 ppm in the single crystal castings made from the alloys. As another variation, in the case of large industrial gas turbine (IGT) single crystal applications where low angle boundary (LAB) strengthening is required up to 12 degrees, carbon and boron additions are targeted in the range from about 0.02% to 0.05% and 40-100 ppm, respectively.

The invention will be described with respect to certain illustrative, non-limiting embodiments that will facilitate a better understanding.

A 400 lb 100% virgin initial heat of CMSX®-7 alloy was melted in January 2011 in the CM V-5 Consarc VIM furnace using aim chemistry to CM KH Jan. 3, 2011 (CM CRMP #81-1700 Issue 1). The heat (5V0424) chemistry is shown in Table 2.

Two molds (#s 912 and 913) of SX NNS DL-10 test bars were cast to CMSX-4® casting parameters by Rolls-Royce Corporation (SCFO). DL-10 test bar yield at 23 fully acceptable out of a total 24 cast was excellent. A mold (#53701) of solid HP2 turbine blades were also SX cast by SCFO using CMSX-4® casting parameters with typical casting yields for this production component.

These DL-10 test bars and turbine blades were solutioned/homogenized+double aged heat treated at CM as follows—based on solutioning/homogenization studies on CMSX®-7 test bars.

Solution+Homogenization

-   -   2 hrs/2340° F. (1282° C.)+2 hrs/2360° F. (1293° C.)         -   +4 hrs/2380° F. (1304° C.)+4 hrs/2390° F. (1310° C.)         -   +12 hrs/2400° F. (1316° C.) AC—ramping up at 1° F./min.             between steps     -   Double Age         -   4 hrs/2050° F. (1121° C.) A +20 hrs/1600° F. (871° C.) AC

Acceptable microstructure attainment is evident in FIGS. 1-2—complete γ′ solutioning, some remnant γ/γ′ eutectic, no incipient melting and approximately 0.5 μm average cubic, aligned γ′, indicating appropriate γ/γ′ mis-match and γ/γ′inter-facial chemistry, following the 4 hr/2050° F. (1121° C.) high temperature age.

Creep—and stress-rupture specimens were low stress ground and tested by Joliet Metallurgical Labs, with the results to date shown in Table 3 and Table 4. Larson-Miller stress-rupture graphs (FIGS. 3, 4 & 5) show CMSX®-7 has superior and surprisingly good creep strength/stress-rupture life properties, including machined-from-blade (MFB) 0.070″ Ø mini-bar results, compared to CMSX-2/3® alloy (zero Re) up to approximately 1900° F. (1038° C.), with similar properties at 2050° F. (1121° C.). All these properties are surprisingly similar to Rene' N-5 (3% Re) and Rene' N-515 (1.5% Re) alloys (Published GE data) [JOM 62 No 1, pgs 55-57 January 2010]. MFB stress-rupture testing was performed on single crystal solid turbine blades 10 (FIG. 16) cast from alloys as disclosed herein which have facility to machine mini-bars 15 and mini-flat specimens 20.

Phase stability is surprisingly good with absolutely no TCP phases apparent in the post-test creep/stress rupture bars examined to date (FIGS. 6-13 inclusive).

Burner rig dynamic, cyclic oxidation and hot corrosion (sulfidation) testing is currently scheduled at a major turbine engine company. The MFB 0.020″ thick gage mini-flat results at 12 ksi/2000° F. (Table 4, FIG. 5) indicate good bare high temperature oxidation resistance for this alloy.

CMSX-7 Tensile Properties

The alloy shows very high tensile strength (up to 200 ksi (1379 MPa) UTS at 1400° F. (760° C.)) and 0.2% proof stress (up 191 ksi (1318 MPa) at the same temperature and good ductility (Table 5, FIGS. 17 & 18). The exceptionally high UTS and 0.2% PS at 1400° F. (760° C.) indicates strain hardening at this temperature, possibly due to further secondary or tertiary γ′ precipitation in the γ channels at this temperature impeding dislocation movement —the ductility at this maximum strength level is in the range of 13% elongation (4D) and 17% reduction in area (RA).

TABLE 1 CHEMISTRY (WT %/ppm) SPECIFICATIONS CMSX ®-7 ALLOY Aero engine Applications C 100 ppm Ti .60-.90 Si .04% Max W 8.5-9.8 Mn .01% Max Zr 150 ppm Max S 3 ppm Max Re .15% Max Al 5.60-5.85 Cu .01% Max B 30 ppm Max Fe .15% Max Cb (Nb) .10% Max V .10% Max Co 9.4-9.9 Ru .10% Max Cr 5.0-6.0 Pt .15% Max Hf .08-.35 Pd .15% Max Mo .50-.70 Mg 200 ppm Max Ni Balance [N] 5 ppm Max Ta 8.0-9.0 [O] 5 ppm Max Enhanced oxidation resistance/coating and thermal barrier coating (TBC) life S 0.5 ppm max La + Y 5-80 ppm (In the SX castings). Industrial Gas Turbine (IGT) SX Applications Low angle boundary (LAB) Strengthened up to 12°. C 0.02-0.05% Max B 40-100 ppm Max TRACE ELEMENT CONTROLS - ALL APPLICATIONS Ag 2 ppm Max Hg 2 ppm Max Bi .2 ppm Max Cd 2 ppm Max Ga 10 ppm Max Ge 2 ppm Max Ca 25 ppm Max Au 2 ppm Max Pb 1 ppm Max In 2 ppm Max Se .5 ppm Max Na 20 ppm Max Te .2 ppm Max K 10 ppm Max Tl .2 ppm Max Ba 10 ppm Max Sn 10 ppm Max P 30 ppm Max Sb 2 ppm Max U 2 ppm Max As 2 ppm Max Th 2 ppm Max Zn 5 ppm Max Density: 8.79 gms/cc.

TABLE 2 HEAT #5V0424 CMSX ®-7 - 100% VIRGIN CHEMISTRY (WT ppm/%) C   17 ppm Re <.05 Si <.02 Cu <.001 Mn <.001 Fe .012 S    1 ppm V <.005 Al 5.80 Ru <.01 B <20 ppm Pt <.001 Cb (Nb) <.05 Pd <.001 Co 9.7 Mg <100 ppm    Cr 5.8 [N] 3 ppm Hf .29 [O] 2 ppm Mo .60 Y <.001 Ni Balance La <.001 Ta 8.6 Ce <.002 Ti .82 W 9.0 Zr <25 ppm Ag <.4 ppm Bi <.2 ppm Ga <10 ppm Ca <25 ppm Pb <.5 ppm Se <.5 ppm Te <.2 ppm Tl <.2 ppm Sn <2 ppm Sb <1 ppm As <1 ppm Zn <1 ppm Hg <2 ppm Cd <.2 ppm Ge <1 ppm Au <.5 ppm In <.2 ppm Na <10 ppm K <5 ppm Ba <10 ppm P 6 ppm U <.5 ppm Th <1 ppm

TABLE 3 CMSX-7 Heat 5V0424 Molds 912/913 (DL-10 s) - RR SCFO [Indy] - LA11753 (Joliet 8935/CM-354) K912/L912 - LA 11773 (Joliet 8979/CM-356) Fully Heat Treated - Solution + double age - 2050° F. primary age Creep-Rupture Time Time Rupture % % to 1% to 2% Test Condition ID Life, hrs Elong RA Creep Creep 1562° F./94.4 ksi A912 100.9 22.4 28.8 5.9 19.8 [850° C./651 MPa] A913 100.8 18.4 27.3 7.0 22.3 1800° F./36.0 ksi B912 147.2 41.8 14.7 58.4 71.1 [982° C./248 MPa] B913 151.1 44.6 49.6 58.4 70.4 1922° F./27.6 ksi C912 53.9 43.6 46.9 19.3 24.4 [1050° C./190 MPa] C913 46.0 37.1 49.7 15.8 20.6 1950° F./18.0 ksi L912 224.9 37.0 62.3 92.4 112.3 [1066° C./124 MPa] 2000° F./12.0 ksi K912 860.3 22.1 54.5 538.1 607.2 [1093° C./83 MPa] Stress-Rupture Rupture % % Test Condition ID Life, hrs Elong RA 2050° F./15.0 ksi D912 141.6 32.4 52.6 [1121° C./103 MPa] E912 130.2 31.4 55.0 Machining and Testing Source: Joliet Metallurgical Laboratory

TABLE 4 CMSX ®-7 Heat 5V0424 Mold 53701 - HP2 Solid Turbine Blades RR SCFO [Indy] - LA11773 (Joliet 8980/CM-357) Fully Heat Treated - Solution + double age - 2050° F. primary age MFB (LLE) Stress-Rupture Mini Bars [0.070″ Ø Gage, shown in FIG. 16] Rupture % % Test Condition ID Life, hrs Elong RA 1562° F./72.5 ksi 53701U-B 783.4 33.3 28.9 [850° C./500 MPa] 1600° F./65.0 ksi 53701V-B 437.9 32.8 33.7 [871° C./448 MPa] 1800° F./40.0 ksi 53701S-B 84.1 39.5 47.8 [982° C./276 MPa] 1850° F./38.0 ksi 53701T-B 43.2 38.5 37.8 [1010° C./262 MPa] 1900° F./25.0 ksi 53701Y-B 105.8 36.1 28.5 [1038° C./172 MPa] 1904° F./21.0 ksi 53701Z-B 238.4 59.3 44.5 [1040° C./145 MPa] MFB (LTE) Mini Flats [0.020″ Thick Gage, shown in FIG. 16] Rupture % Test Condition ID Life, hrs Elong 1800° F./30.0 ksi 53701S-F 387.3 42.7 [982° C./207 MPa] 53701T-F 344.4 35.0 1904° F./21.0 ksi 53701U-F 219.8 38.1 [1040° C./145 MPa] 53701V-F 189.5 33.3 2000° F./12.0 ksi 53701Y-F 880.0 32.4 [1093° C./83 MPa] 53701Z-F 578.8 13.9 Machining and Testing Source: Joliet Metallurgical Laboratory

TABLE 5 CMSX-7 - Heat 5V0424 Molds 063/064 - RR SCFO [Indy] - LA 11753 (Joliet 8935/CM-354) Fully Heat Treated - Solution + Double Age - 2050° F. Primary Age TENSILE TEST RESULTS 0.2% PS UTS % Elona % Test Temperature ID (ksi) (ksi) (4D) RA 70° F. (21° C.) A063 135.1 154.6 11.4 13.1 A064 129.1 168.1 11.3 15.3 800° F. (430° C.) B063 154.2 163.8 9.1 9.5 B064 151.6 162.2 9.0 9.8 1000° F. (538° C.) K063 149.7 163.3 8.0 10.0 K064 148.6 163.2 8.0 13.9 1100° F. (593° C.) L063 149.6 172.0 7.7 10.7 L064 151.9 177.1 6.5 9.3 1200° F. (649° C.) M063 153.8 175.5 7.8 19.2 M064 149.0 172.0 5.4 20.4 1400° F. (760° C.) N063 190.4 198.9 14.9 16.8 N064 191.7 199.7 12.0 17.9 1600° F. (871° C.) P063 131.3 148.4 31.9 33.2 P064 133.9 145.3 29.8 36.1 1700° F. (927° C.) R063 112.8 136.9 27.5 27.7 R064 115.0 126.4 27.0 31.7 1800° F. (982° C.) Y063 112.4 123.3 19.5 23.0 W064 106.9 120.3 23.6 23.8 1900° F. (1038° C.) Z063 88.3 94.6 32.5 52.2 X064 78.9 90.2 36.6 51.4 [100 ksi = 690 Mpa] Machining & Testing Source: Joliet Metallurgical Laboratory

TABLE 6 HEAT #5V0459 CMSX ®-7 Mod B - 100% VIRGIN CHEMISTRY (WT ppm/%) C 9 ppm Re <.05 Si <.02 Cu <.001 Mn <.001 Fe .015 S 1 ppm V <.005 Al 5.780 Ru <.01 B <25 ppm  Pt <.001 Cb <.05 Pd <.001 (Nb) Mg <100 ppm    Co 9.7 [N] 1 ppm Cr 5.6 [O] 1 ppm Hf .30 Y <.001 Mo .59 La <.001 Ni Balance Ce <.002 Ta 8.4 Ti .70 W 9.3 Zr <25 ppm  Ag <.4 ppm Bi <.2 ppm Ga <10 ppm Ca <25 ppm Pb <.5 ppm Se <.5 ppm Te <.2 ppm Tl <.2 ppm Sn <2 ppm Sb <1 ppm As <1 ppm Zn <1 ppm Hg <2 ppm Cd <.2 ppm Ge <1 ppm Au <.5 ppm In <.2 ppm Na <10 ppm K <5 ppm P 8 ppm U <.5 ppm Th <1 ppm

TABLE 7 CMSX-7 MOD B - Heat 5V0459 Molds 923/924 - (DL-10 s) - RR SCFO [Indy] - LA11834 (Joliet 9156/CM-368) [DL-10s] Fully Heat Treated - Solution + double age Creep-Rupture Rupture % % 1% 2% Test Condition ID Life, hrs Elong RA Creep Creep 1562° F./72.5 ksi A923 972.7 19.6 25.2 298.3 463.7 [850° C./500 MPa] H923 861.8 20.6 27.6 275.7 411.2 1600° F./65.0 ksi B923 667.4 21.8 26.5 224.6 323.0 [871° C./448 MPa] R924 670.4 19.8 31.3 262.8 363.8 1800° F./36.0 ksi C923 139.2 37.9 45.6 56.2 68.0 [982° C./248 MPa] N924 151.5 31.6 38.0 64.6 77.2 1800° F./40.0 ksi D923 97.4 34.8 41.5 39.4 48.0 [982° C./276 MPa] M24 106.3 28.8 33.7 45.3 55.2 1850° F./38.0 ksi E923 51.7 34.3 35.2 21.1 25.6 [1010° C./262 MPa] L924 54.1 36.5 36.6 21.2 26.0 1900° F./25.0 ksi J923 103.0 25.1 43.5 39.5 49.3 [1038° C./172 MPa] H924 111.2 27.6 40.2 38.6 51.1 1904° F./21.0 ksi K923 240.2 31.0 47.1 90.6 112.9 [1040° C./145 MPa] E924 245.7 43.4 46.7 86.5 109.1 1950° F./18.0 ksi L923 260.5 27.4 37.5 86.0 112.4 [1066° C./124 MPa] D924 219.1 38.4 41.7 79.8 101.5 Stress-Rupture Rupture % % Test Condition ID Life, hrs Elong RA 2000° F./12.0 ksi M923 1176.5 34.4 42.4 [1093° C./83 MPa] B924 960.4 37.4 42.9 2050° F./15.0 ksi N923 143.7 20.7 36.5 [1121° C./103 MPa] A924 135.8 26.3 38.2 Machining and Testing Source: Joliet Metallurgical Laboratory

A further heat (5V0459) of 100% Virgin (470 lbs) designated CMSX®-7 Mod B was melted in May 2011 in the CM V-5 Consarc VIM furnace using aim chemistry to CM KH Apr. 13, 2011 (CM CRMP #81-1703 Issue 1). The heat (5V0459) chemistry is shown in Table 6.

Two molds (#s 923 & 924) of SX NNS DL-10 test bars were cast to CMSX-4® casting parameters by Rolls-Royce Corporation (SCFO). DL-10 test bar yield at 22 fully acceptable out of a total 24 cast was excellent.

These DL-10 test bars were solutioned/homogenized+double aged heat treated at Cannon-Muskegon Corporation as follows—based on solutioning/homogenization studies on CMSX®-7 Mod B test bars.

Solutioning and Homogenization

-   -   2 hrs/2360° F. (1293° C.)+2 hrs/2370° F. (1299° C.)         -   +2 hrs/2380° F. (1304° C.)+12 hrs/2390° F. (1310° C.)             AC—ramping up at 1° F./min.     -   Double Age Heat Treatment         -   4 hrs/2050° F. (1121° C.) AC         -   +20 hrs/1600° F. (871° C.) AC

Acceptable microstructure attainment is evident FIGS. 14 & 15, almost complete γ′ solutioning, remnant γ/γ′ eutectic, no incipient melting and approximately 0.45 μm average cubic aligned γ′, indicating appropriate γ/γ mismatch and γ/γ′ inter-facial chemistry, following the 4 hr/2050° F. (1121° C.) high temperature age.

The creep-rupture properties of CMSX®-7 Mod B are very similar to that of CMSX®-7, with no apparent advantage (Table 7).

Post-test microstructures from a longer term, high temperature stress-rupture test [2000° F./12 ksi (1093° C./83 MPa)/1176.5 hours] are shown (FIGS. 19A-19C) to exhibit good phase stability, with negligible TCP phase (“needles”) apparent, combined with good stress-rupture life and rupture ductility (34% elongation (4D)) and 42% RA (FIGS. 19A-20C).

The embodiments disclosed herein are non-limiting examples that are provided to illustrate and facilitate a better understanding, the scope of the invention being defined by the appending claims as properly construed under the patent laws, including the doctrine of equivalents. 

What is claimed is:
 1. A nickel-base superalloy for single crystal casting comprising: 5.60% to 5.85% aluminum by weight; 9.4% to 9.9% cobalt by weight; 5.0% to 6.0% chromium by weight; 0.08% to 0.35% hafnium by weight; 0.50% to 0.70% molybdenum by weight; 8.0% to 9.0% tantalum by weight; 0.60% to 0.90% titanium by weight; 8.5% to 9.8% tungsten by weight; and the balance comprising nickel and minor amounts of incidental elements, the total amount of incidental elements being about 1% or less by weight.
 2. A nickel-base superalloy for single crystal casting according to claim 1, in which the incidental elements are controlled to maximums of 100 ppm carbon, 0.04% silicon, 0.01% manganese, 3 ppm sulfur, 30 ppm phosphorous, 30 ppm boron, 0.1% niobium, 150 ppm zirconium, 0.15% rhenium, 0.01% copper, 0.15% iron, 0.1% vanadium, 0.1% ruthenium, 0.15% platinum, 0.15% palladium, 200 ppm magnesium, 5 ppm nitrogen, and 5 ppm oxygen, each of any other incidental elements being present as a trace element at a maximum of about 25 ppm.
 3. A nickel-base superalloy for single crystal casting according to claim 2, in which the trace elements are controlled to maximums of 2 ppm silver, 0.2 ppm bismuth, 10 ppm gallium, 25 ppm calcium, 1 ppm lead, 0.5 ppm selenium, 0.2 ppm tellurium, 0.2 ppm thallium, 10 ppm tin, 2 ppm antimony, 2 ppm arsenic, 5 ppm zinc, 2 ppm mercury, 2 ppm cadmium, 2 ppm germanium, 2 ppm gold, 2 ppm indium, 20 ppm sodium, 10 ppm potassium, 10 ppm barium, 30 ppm phosphorous, 2 ppm uranium, and 2 ppm thorium.
 4. A nickel-base superalloy for single crystal casting according to claim 1, containing a maximum amount of sulfur of 0.5 ppm, and further comprising an amount of lanthanum and yttrium that is targeted to achieve a total lanthanum and yttrium content that is from about 5 ppm to 80 ppm in a single crystal casting.
 5. A nickel-base superalloy for single crystal casting according to claim 1, containing from 0.02% to 0.05% carbon by weight, and from 40 ppm to 100 ppm boron.
 6. A nickel-base superalloy for single crystal casting according to claim 1, having a density about 8.8 gms/cc (kg/dm³).
 7. A single crystal component cast from an alloy according to claim
 1. 8. A single crystal component according to claim 7 that is a gas turbine component.
 9. A single crystal component according to claim 7 that is a blade, a vane, or a seal segment for a gas turbine. 